Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The importance of the lateral habenula-dorsal raphe pathway in the control of in vivo [3H]serotonin release in the cat basal ganglia was examined using the push-pull cannula technique and an isotopic method for the estimation of [3H]serotonin continuously formed from [3H]tryptophan. [3H]Serotonin was measured in both caudate nuclei and substantiae nigra and, in some cases, in the dorsal raphe. Electrical stimulation of the lateral habenula decreased [3H]serotonin release in all structures studied. Blockade of the GABA inhibitory pathway to the lateral habenula by the local application of picrotoxin reduced [3H]serotonin release in both substantiae nigra and increased release of the 3H-amine in the dorsal raphe but was without effect on [3H]serotonin release in either caudate nucleus. This inhibition of nigral [3H]serotonin release was antagonized by simultaneous application of picrotoxin to the dorsal raphe. Substance P delivery to the dorsal raphe produced the same effects on [3H]serotonin release as described for picrotoxin application to the lateral habenula except that inhibition of nigral [3H]serotonin release was not prevented by local co-administration of picrotoxin. These results suggest that the lateral habenula can control serotonergic transmission in the basal ganglia and that this regulation may be different for those serotonergic neurons innervating the caudate nucleus versus those projecting to the substantia nigra.
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PMID:Involvement of lateral habenula-dorsal raphe neurons in the differential regulation of striatal and nigral serotonergic transmission cats. 618 Jan 48

A potassium-evoked release of 5-[3H]hydroxytryptamine (5-HT), newly synthesized from [3H]tryptophan, was obtained from slices of the subnucleus caudalis of rat spinal trigeminal nucleus by means of an in vitro perfusion system. This release was dose-dependent and calcium-sensitive and quantitatively comparable to the 5-HT release in substantia nigra. The putative transmitter of the primary sensory afferents, substance P, stimulates the spontaneous 5-HT release, whereas another peptide, neurotensin, has no effect.
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PMID:In vitro release of 5-[3H]hydroxytryptamine from rat spinal trigeminal nucleus. 618 5

The effects of peptides on gastric emptying of a liquid meal were studied in rats. Gastric emptying was found to be delayed following intraperitoneal injection of the octapeptide of cholecystokinin (CCK-8). Vasoactive intestinal peptide did not effect emptying, while substance P and neurotensin caused a moderate acceleration in gastric emptying. After oral administration of a solution containing the amino acids tryptophan and phenylalanine, but not glycine, a statistically significant inhibition of gastric emptying was observed. Our results suggest an involvement of CCK in the regulation of gastric emptying.
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PMID:Effects of peptides on gastric emptying. 620 51

The nature of the putative transmitter(s) mediating the non-cholinergic excitatory post-synaptic potential (e.p.s.p.) described in the preceding paper was investigated by means of electrophysiological, pharmacological and immunohistochemical methods. Serotonin (1-10 microM) when applied by superfusion caused a slow depolarization that closely mimicked the synaptic response in about 60% of the coeliac neurones that exhibited a non-cholinergic e.p.s.p. The serotonin depolarization evoked in low-Ca2+, high-Mg2+ solution or in a Krebs solution containing cholinergic antagonists was quantitatively similar to that elicited in normal Krebs solution. When compared in the same neurones the membrane resistance change during the course of the serotonin depolarization and of the non-cholinergic e.p.s.p., as well as their respective responses to conditioning polarization, were similar. The non-cholinergic e.p.s.p. was reversibly abolished during serotonin-induced depolarization; the blockade persisted when the membrane potential was restored to the resting level by hyperpolarizing current. The serotonin depolarization as well as the non-cholinergic e.p.s.p. were reversibly suppressed by cyproheptadine (20-50 microM), a serotonin antagonist, and enhanced by fluoxetine (30-50 microM), a serotonin reuptake inhibitor. On the other hand, pre-treating the ganglia with L-tryptophan (50 microM), a precursor of serotonin, preferentially augmented the synaptically induced response. A portion of the neurones (15%) were depolarized by substance P (1 microM) which also reversibly desensitized the non-cholinergic e.p.s.p. elicited in these neurones. The remaining neurones (25%) were insensitive to either serotonin or substance P, and the non-cholinergic e.p.s.p.s elicited in these cells were likewise not appreciably affected by these two agents. Furthermore, cyproheptadine, fluoxetine and L-tryptophan had no significant effect on the non-cholinergic e.p.s.p.s elicited in serotonin-insensitive neurones. Using the immunohistofluorescent techniques, dense but unevenly distributed serotonin immunoreactive nerve fibres could be observed surrounding many coeliac neurones. Immunoreactivity was not observed in the ganglia incubated with antisera pre-absorbed with excess serotonin. Collectively our results suggest that serotonin is the mediator of non-cholinergic e.p.s.p.s. elicited in about 60% of coeliac neurones sampled in this study, and that in the remaining neurones the slow depolarization may be generated by substance P and/or some unknown transmitter(s).
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PMID:Evidence for a serotonin-mediated slow excitatory potential in the guinea-pig coeliac ganglia. 620 46

Five undeca- and six C-terminal heptapeptide substance P (SP) analogues were tested for their capacity to block the contractile effect of SP on the guinea-pig isolated taenia coli. They had one feature in common, namely substitutions in positions 7 and 9 in the SP molecule. In the majority of analogues D-tryptophan was used for these substitutions. All analogues tested were found to be competitive antagonists to exogenous SP and to be capable of blocking the electrically induced non-cholinergic, non-adrenergic neuronal contraction of the taenia. Of the undecapeptides, (D-Arg1, D-Pro2, D-Trp7,9, Leu11) SP and (D-Arg1, D-Trp7,9, Leu11) SP (Spantide) had the highest pA2 value, 7.1-7.2, and the lowest IC50 value, 10(-6) M. The pA2 values of the heptapeptides were generally lower. Three of the most potent antagonists were tested for specificity and found to block the smooth muscle contraction induced by SP, physalaemin, eledoisin and bombesin but not that induced by bradykinin, carbachol, 5-hydroxytryptamine, histamine, prostaglandins and vasopressin. The SP antagonists were also tested for spasmogenic effect on the taenia and for their capacity to release histamine from rat isolated peritoneal mast cells. The spasmogenic activity displayed by most of the SP antagonists tested is likely to be related to their ability to release histamine since the contractile response was reduced by mepyramine, a histamine H1-receptor antagonist. (D-Arg1, D-Trp7,9, Leu11) SP was notable for combining a high antagonistic potency with a weak spasmogenic effect (and poor histamine releasing effect).
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PMID:Biological evaluation of substance P antagonists. 620 86

We have recently shown that a series of N-acyl-L-tryptophan benzyl esters are potent substance P antagonists (Macleod, A. M., Merchant, K. J., Cascieri, M. A., Sadowski, S., Ber, E., Swain, C. J., and Baker, R. (1993) J. Med Chem. 14, 2044-2045). We now report the detailed characterization of the interaction of N-acetyl-L-tryptophan-3,5-bistrifluoromethyl benzyl ester (L-732,138) with the human neurokinin-1 (NK-1) receptor. L-732,138 inhibits the binding of 125I-substance P to the cloned human NK1 receptor expressed in Chinese hamster ovary cells with an IC50 of 2.3 +/- 0.7 nM. In contrast, it has 200-fold lower affinity for the cloned rat NK-1 receptor and has > 1000-fold lower affinity for the human NK-2 and NK-3 receptors. L-732,138 acts as a competitive antagonist of substance P, as shown by functional Schild analysis of the inhibition of substance P-induced inositol phosphate synthesis, by kinetic analysis of the dissociation rate, and by thermodynamic analysis of the equilibrium binding of 125I-substance P to the NK-1 receptor. L-732,138 also competitively inhibits the binding of the quinuclidine amine antagonist, [125I]L-703,606, to the receptor. The compound has 230- and 10-fold reduced affinity for mutant NK-1 receptors in which histidine 265 or histidine 197, respectively, are replaced with alanine. We have previously shown that these residues play key roles in the binding of quinuclidine antagonists to the NK-1 receptor. These results suggest that the tryptophan and quinuclidine series of NK-1 antagonists bind to similar binding sites on the human NK-1 receptor.
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PMID:Characterization of the interaction of N-acyl-L-tryptophan benzyl ester neurokinin antagonists with the human neurokinin-1 receptor. 750 7

The effects of 1-week drug treatment on the brain contents of neuropeptides were investigated. The cholecystokinin (CCK) concentrations in the hypothalamus were significantly decreased by tryptophan treatment but not by imipramine and cyproheptadine, which changed the serotonergic function. Proglumide, the CCK antagonist, induced in the hypothalamic and hippocampal-striatal areas an increase in CCK concentration, which was not reversed in the presence of tryptophan. Dynorphin and substance P(SP) concentrations were also modified by proglumide treatment.
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PMID:Brain cholecystokinin octopeptide (CCK-8) concentrations: effect of tryptophan and other serotonergic agents. 751 98

As part of a program of screening the Merck sample collection, N-ethyl-L-tryptophan benzyl ester was identified as a weak antagonist at the substance P (NK1) receptor. Structure-activity studies showed that the indole ring system could be replaced by 3,4-dichlorophenyl, alpha- or beta-naphthyl, or benzthiophene with retention or only small loss of affinity. It was found that acylation of the tryptophan nitrogen gave compounds with higher affinity than N-ethyl or other basic amines. Optimization of substitution on the benzyl ester led to the identification of the 3,5-bis-(trifluoromethyl)benzyl ester of N-acetyl-L-tryptophan 26 as a potent and selective substance P receptor antagonist. Compound 26 blocked substance P induced dermal extravasation in vivo and was the most potent compound from this structurally novel class of antagonists which further adds to the diversity of small molecules that bind to the (NK1) receptor.
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PMID:Identification of L-tryptophan derivatives with potent and selective antagonist activity at the NK1 receptor. 751 63

WIN 64821, a nonpeptide neurokinin antagonist, was isolated from a strain of Aspergillus sp., SC319. The compound was produced in different fermentation media with greatest yields observed when the culture was grown in a synthetic medium supplemented with L-tryptophan and L-phenylalanine. After 6 days fermentation, yields greater than 600 mg/liter were obtained. Two analogs of WIN 64821 were also identified in the culture extracts and subsequently tested for biological activity. WIN 64821 was the most potent compound isolated from this culture and exhibited activity as a substance P-binding inhibitor with submicromolar potency against the human neurokinin 1 receptor.
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PMID:WIN 64821, a novel neurokinin antagonist produced by an Aspergillus sp. I. Fermentation and isolation. 751 37

WIN 64821 (1) is a substance P (SP) antagonist isolated from a fungal culture (Aspergillus sp., SC319). It is a symmetrical dimer biosynthesized from four aromatic amino acid molecules: each equivalent half of the dimer is constructed from one molecule of phenylalanine (Phe) and one molecule of tryptophan (Trp). Feeding analogs of Phe, Trp, and other amino acids to intact cells of SC319 has yielded 36 biosynthetic analogs of WIN 64821. The analogs fall into three categories: substitutions on the indoline ring, substitutions on the Phe-derived phenyl ring, and replacement of the phenyl ring by an aliphatic group. In addition, these directed biosynthesis experiments generated asymmetrical dimers (derived from three amino acids) and, often, symmetrical dimers (derived from two amino acids). The relative SP binding affinities of several analogs suggest involvement of both the indoline and phenyl moieties in SP receptor binding.
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PMID:WIN 64821, a novel neurokinin antagonist produced by an Aspergillus sp. III. Biosynthetic analogs. 751 39


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